The source of residual stresses in the vicinity of a weld may be expressed in terms of inherent strains. The characteristics of the inherent strain distributions in butt welds are investigated. It is found that the patterns vary little with changes in the welding conditions and sizes of the welded plates. With some assumptions, simple formulas are derived for the distribution and magnitude of inherent strain in a butt weld. A method of predicting the residual stress in a butt-welded plate using the characteristics of inherent strain distributions is presented. The validity of the method is confirmed by thermal elasto-plastic analysis using the finite element method (FEM).

In order to develop a predicting method of residual stresses in fillet welded T- and I-joints, a concept of inherent strain, being regarded as a source of the residual stresses, was introduced. With the proposed method, the residual stress of an interested weldment may be predicted by performing an elastic analysis, in which the inherent strain is replaced to equivalent distributed loads. The inherent strain distributions in various welded T- and I-joints were investigated by numerical simulations. The results showed that the inherent strains distributing in flange side and in web side of the several joints are almost the same. The inherent strains vary not only with the average temperature rise due to welding, but with the geometric ratio of the joints. Being simplified by a trapezoid curve, the inherent strain distribution in a fillet weld was expressed by formulas, in which heat input, material properties, and geometric dimensions were taken into account. Welding residual stresses in T- and I-joints, predicted by the proposed method employing the derived formulas, were compared with those obtained by thermal elasto-plastic analysis, and good agreement was recognized. The validity of the proposed method was also confirmed by experiments.

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The effects of two levels of irrigation water (100%, 60%) and buried underground pipe depths (0.8 m, 0.6 m) under rain shelters' conditions on yield and some quality parameters of tomato were investigated. A fully randomized factorial experiment was conducted between April and August in 2011 and 2012 at Hohai University. It was found that drainage treatments enhanced biomass production, whereas soil desiccation led to biomass reduction. At 60 cm buried underground pipe depths, the drought treatments increased the mean root weight and root-shoot ratio by 14% and 39%, respectively. The main effects of drainage treatments on the fruit quality were increases in total soluble solids (TSS), soluble sugar (SS), and vitamin C (VC) compared to the control. In addition, drainage treatments increased the average yield by 13% and 9%, respectively, in both years. The drought treatments did not significantly alter fruit yield, although mean single fruit weight was slightly reduced. Instead, these treatments tend to have great potential to improve fruit quality (TSS, SS, and VC) to variable extents. In both years, the drought treatment at 60 cm buried underground pipe depths proved to possess the highest comprehensive quality index based on Principal Component Analysis.